1. Field of the Invention
The present invention relates to a method and device for analyzing positions, and more particularly, to a method and device for analyzing positions while neglecting unreal touches.
2. Description of the Prior Art
Touch displays have been widely used in the various electronic devices. One approach is to employ a touch sensitive panel to define a 2-D touch area on the touch display, where sensing information is obtained by scanning along horizontal and vertical axes of the touch panel for determining the touch or proximity of an external object (e.g. a finger) on or near the touch panel. U.S. Pat. No. 4,639,720 discloses a capacitive touch display.
Sensing information can be converted into a plurality of continuous signal values by an analog-to-digital converter (ADC). By comparing signal values before and after the touch or approaching of the external object, the position touched or approached by the external object can be determined.
Generally, a controller controlling the touch panel will first obtain sensing information when there is no external object touching or approaching as a baseline. For example, in a capacitive touch panel, each conductive line corresponds to a respective baseline. The controller determines whether there is an external object touching or approaching by comparing sensing information obtained subsequently with the baseline, and further determines the position of the external object. For example, when there is no external object touching or approaching the touch panel, subsequent sensing information with respect to the baseline will be or close to zero. Thus, the controller can determine whether there is an external object touching or approaching by determining whether the sensing information with respect to the baseline is or close to zero.
As shown in FIG. 1A, when an external object 12 (e.g. a finger) touches or approaches a sensing device 120 of a touch display 10, sensing information of sensors 140 on an axis (e.g. x axis) is converted into signal values as shown in FIG. 1B. Corresponding to the appearance of the finger, the signal values show a waveform or finger profile. The location of the peak 14 of the finger profile indicates the position touched or approached by the finger.
During mutual-capacitance detection, when two fingers of the same hand touch different positions of the sensing device, signals may flow from one finger to the other, resulting in sensing device picking up touch related sensing information at non-touched positions (referred to unreal touches hereinafter) and making wrong judgments. When three or four positions are determined from touches of the two fingers, the system will have difficulty in operating.
Input method using fingers is different from input method using a pen held by a hand. Generally, conductive pens used in capacitive sensing device require the palm to be held in the air when inputting, it is very different from the normal practice of resting the palm on a surface when writing. Thus, the sensing device needs to be able to distinguish between a touch made by the palm and a touch made by a pen or a finger in order to allow for the normal way of writing adopted by most people.
From the above it is clear that prior art still has shortcomings. In order to solve these problems, efforts have long been made in vain, while ordinary products and methods offering no appropriate structures and methods. Thus, there is a need in the industry for a novel technique that solves these problems.